Concrete Handling in Field: Essential Techniques and Equipment

Department of Civil Engineering

1

Concrete Handling in Field

By:

Nishant Singh Kushwaha

Concrete Handling in field

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.

Most of the material covers in this ppt and

rest if left please refer to

 M.S Shetty book.

Stages of producing

concrete.

3

(1)

Batching

(2)

Mixing

(3)

Transportation

(4)

Placing

(5)

Compacting

(6)

Curing

(7)

Finishing

(1)

Batching

4

(a)

Volume

batching

(b)

weight

Baching

Volume

batching

5



Volume batching 

is 

not good

method



Moist 

sand in 

loose condition weights

less

than the 

same 

volume 

of 

dry

sand.



Practiced for small

work.



For 

quality 

work 

,weigh batching

is

practiced.

VOLUME

BATCH

Gauge

box



Various gauge boxes of 

different 

volumes are

used.

6

Weigh Batch

Machine

7

Weigh

batching

8



Weigh batching is correct

method



Facilitates accuracy, 

flexibility 

&

simplicity

Different batching machine are available

:

(a)

manual machines & (b) Automatic

machines

Manual machine

:



Has two

buckets



Buckets mounted on common spindle about which they

rotate.



One is loaded while 

other 

is discharged in

mixer.



Spring loaded dials indicate the

weight.

Automatic weigh

batch

9



For 

large

works



Over 

head hopper and 

discharges

into

mixer.



Useful in 

ready 

mix concrete

plant



Recorders for

weight



Calibration 

is 

required 

from 

time 

to

time.

(2)

MIXING

10

Mixing 

of cement,sand aggregates

should

ensure

that:



The 

mass 

is

homogeneous



Uniform 

in

color



consistent

MIXING METHODS

:

(1)

Hand

mixing

(2)

Machine

mixing

11

Hand

mixing



Practiced 

for small 

scale work

(small

house, 

repairing 

of 

house

etc)



10 % extra cement is 

added to

compensate inferior 

concrete 

produced

by

this method.



Spread 

fine 

& coarse 

aggregate

in

alternate

layer



Spread cement over

it



Mix with shovel till 

uniform color

is

achieved

Machine

mixing

13



Medium 

& 

large 

scale work use

machine

mixing



Mixing 

is 

efficient, economical 

& 

produce

quality concrete.

Type of

mixer:

(a)

Batch mixer : 

batch 

by 

batch 

with

time

interval

(b)

Continuous mixer: continuously 

mixed

&

discharged (in 

dam

construction)

CONCRETE

MIXER

14

(1)

Pan

type

(2)

drum

Type:

(a)

tilting

(b)

Non

–tilting

(c)

Reversing

PAN

MIXER

15

PAN

MIXER

16

A 

forced movement pan mixer has blades

that are 

fixed to an assembly 

that

agitates

the concrete 

throughout 

the 

pan 

as 

the

vertical shaft

rotates.

DRUM

MIXER

17



As 

per 

IS: 

1791-1985 

mixers are

designated 

by 

number 

which

shows

capacity 

(liters) 

of

batch:

a)

Tilting 

: 

85 

T, 100T, 140 

T,

200T

b)

Non 

tilting 

: 200 NT,280 NT, 

375 

NT,

500

NT, 

1000

R

c)

Reversing : 

200 

R, 

280 

R, 

375 R,500

R,

1000

R

T= 

Tilting, 

NT 

=non tilting,

R=Reversing

TILTING

MIXER

18

TILTING

MIXER

19



Internal blades lift and tumble the

ingredients onto

itself.

Two 

primary 

types

exist:



horizontal (one end has and opening

for

charging and 

a 

different end for

discharging)



single drum (materials 

are 

charged

and

discharged 

through 

a 

single

opening).

NON TILTING

MIXER

20

NON TILTING

MIXER

21



Single drum rotating about 

a 

horizontal

axis.



Fixed 

blades work the 

concrete towards

the 

discharge end 

of 

the mixer, in 

order

to

provide a 

rapid 

rate of

discharge.

REVERSING

MIXER

22

REVERSING

MIXER

23



The entire 

drum rotates 

around its 

axis 

as

materials are 

loaded through 

a 

charge chute 

at

one 

end 

of the drum and exit through a

discharge chute 

at the 

opposite 

end 

of 

the

drum.



Mixing blades 

are mounted 

on the 

inside surface

of the drum and 

as 

the drum rotates the blades

mix by lifting and 

dropping 

the materials 

during

each

 rotation.



Once the 

materials 

are 

sufficiently 

mixed the

rotation of 

the drum is reversed 

and 

the blade

arrangement pushes the concrete through to the

discharge end 

of the mixer.

Sequence of charging

drum

24



First 

half quantity 

of coarse 

aggregate

is

placed 

in

skip



Over it 

half quantity of

sand



On 

that full quantity 

of

cement



Over it 

balance quantity 

of coarse &

fine

aggregates 

is

place.



This prevents spillage 

of 

cement 

in

air

while 

discharging 

in

drum



25 

% 

Water 

is placed in drum 

and 

then

mix 

from 

skip is discharged in the

drum



This prevents 

sticking of cement on

blades



75 

water 

is 

immediately poured after

placing 

mix 

material (cement 

sand etc)

in

drum.

25

25

Mixing

time



In 

small machine, 

mixing time

varies

between 1-2

minutes



In 

Ready Mix Cement 

mixer –

15-30

seconds



RPM 

of 

drum 

:

15-20



Compressive 

strength 

of concrete

increases with 

increase 

in 

mixing time

but

after 

2 

minutes increase 

in compressive

stre

n

g

t

h

is n

o

t si

g

n

K

i

A

f

S

i

-

2

c

0

1

a

2

n

t.

26



If 

concrete 

is 

not used after mixing 

it 

may

set



But when concrete is 

agitated 

on 

time

to

time 

in 

drum setting time rule does not

follow.

27

Retempering of concrete

:



Some time 

concrete from RMC 

plant is

not

delivered 

to site 

due 

to traffic

congestion



Concrete 

becomes 

stiff 

and

becomes

unworkable



Site 

engineers 

can 

reject 

the concrete

if

delay 

is

more



If it can be 

of used 

then 

small 

volume 

of

water 

is 

added and again agitated 

in 

the

drum. This 

is 

called RETEMPERING

OF

CONCRETE.

MANUFACTURING

OF

29

CONCRETE



With same 

material if 

care is 

not

taken,

resulting concrete will be 

bad

concrete



What are good rules 

to 

make good

quality

concrete.

TRANSPORTATION OF

CONCRETE

30

Precaution 

in concrete

transportation:



Homogeneity 

of conc. 

Mass 

is

maintained



Movement 

of 

hand trolly 

or truck on

rough

road 

surface makes

vibrations



This results 

in 

deposition 

of

heavy

aggregates

at bottom 

of

truck



Water 

& 

cement 

slurry comes 

on

top.

METHODS OF

TRANSPORTATION

31

1.

Mortar

Pan

2.

Wheel

barrow

3.

Truck 

Mixer 

&

 dumpers

4.

Crane, Bucket 

& 

rope

way

5.

Belt conveyors

6.

Chutes

7.

Skip 

&

hoist

8.

Transit

 Mixer

9.

Pump 

&

 pipeline

10.

Helicopter

MORTAR

PAN

32



Common method 

in

India



More labour

required



Segregation 

of concrete is

less



Greater 

surface 

area 

of concrete

is

exposed to sun, concrete

dries.

WHEEL

BARROW

33



When transportation 

of concrete is

at

ground

level.



Movement 

of 

wheel 

on 

rough

road

surface, 

segregates

concrete.



Some wheel barrows have

pneumatic

wheel 

to 

reduce

vibration

CRANE

34



Used 

for transporting 

concrete

above

ground

level.



For 

high rise

buildings.



Cranes 

are

fast



Can 

move horizontally 

&

vertically



Concrete in skip discharge from

bottom



In bucket concrete is discharged by

tilting.

BUCKET &

ROPEWAY

35

Use

 for 

construction

in:



Valley



Bridge pier 

in

river



Dam

Adva

n

ta

g

e:

Concrete is 

not exposed 

to sun or 

air 

&

no

loss of

water.

Truck Mixer &

dumpers

36



Used 

for 

large concrete

works.



Can travel 

any part 

of

site.



Dumpers

-

2-3 

M

3

Capacity



Trucks – 4 M

3

Capacity



Bottom 

surface of truck is kept

wet



Top of 

truck 

is covered to

prevent

evaporation

BELT

CONVEYORS

37



Limited use in

construction

Advantages:



Can transport large

volume



Very

quick



Can go where access is

limited

Disadvantages

:



On steep slope concrete

segregates.



Exposed to sun for long

time.

CHUTE

38



For transporting 

from 

ground 

level 

to

lower

level. (basement

etc).



Used where 

labour 

can 

not reach due

to

less space in 

trench

etc.



Made 

of

metal



Slope should not 

be < 1 vertical :

2.5

horizontal.

SKIP &

HOIST

39



Labour 

can go 

upto 

3rd or 

4th

floors.



So skip is used for transport vertically

up

(in 

multistory

building).



Skip 

travels 

on vertical

rail.



Skip can 

discharge manually

or

automatically.

TRANSIT

MIXER

40

TRANSIT

MIXER

41



Used for 

long distance travel 

in RMC

plant.



Concrete is 

continuously 

agitated in 

truck 

drum

(2 – 6

rpm).



Also 

transported 

mix 

in dry condition and 

water

is added on 

reaching 

the

destination.



Wet Mix in 

truck 

must 

reach site 

in 

1- 

1.5 hours.



Pumps are 

also fitted 

on 

truck mixer 

to

discharge

concrete.

PUMPS &

PIPELINE

42



Most popular

method



Reliable & good quality pumps are

used.



Mostly operated by

diesel.



Concrete is placed in 

collecting

hopper.



Rotating 

blades 

in hopper pushes concrete

towards

 pipe.



Vacume in 

hose 

pipe 

(600 

mm

Hg)



Rotating 

rollers 

in pump chambers squeeze the

concrete in pipe and 

flow 

of concrete is

started.



Concrete is discharged from other 

end of 

hose

pipe.



Concrete can be pumped upto 400 m height and

2000 m

distance.

SECTION 

OF

PUMP

43

PIP

E

LINE

44

Pipeline 

should

:



Have correct 

diameter 

as 

per

pump

pressure. 

(generally 125

mm)



Have sufficient

thickness



Good

couplings



Poor pipeline 

can cause

blockage.

44

PIPELINE



Thumb 

rule : 

For 

30 

M

3 

/hr concrete 

and

200 

m 

length, dia 

should be 

100

mm.



Length 

> 

500 

m 

then dia 

= 

150

mm.



Dia = 3 

to 

4 

times 

the size of

aggregate



Leaky pipe & 

coupling result 

in escape

of

water /air 

& 

finally block the

concrete.



Vertical pipe 

should 

good

otherwise

difficult 

to 

change 

at

height.



Pump 

is 

kept at 

distance from

building

about 15 

% 

of vertical

length.

KAS-2012

PUMPABLE

CONCRETE

46



Concrete which 

can be 

pushed 

through a 

pipeline

is

called pumpable

concrete.



Friction 

between pipe wall and concrete is

less.



Concrete flows in 

the form of 

plug 

which is separated

from 

pipe wall by a thin layer 

of 

lubricating 

cement

paste.



Flow 

resistant must 

be 

< 

pump

pressure.



If the 

concrete is 

more 

wet then water 

comes out of 

mix

which 

makes more 

resistance 

to 

flow.



Stiff 

and also 

very wet 

concrete is 

not

pumpable.

Design of pumpable

concrete

47



Concrete 

Mix is so 

designed 

that 

all 

material

remain

together.



Mix 

must 

make redial 

movement of 

grout to maintain

lubricating

paste.



Mix should be deformed 

at

bends



Cement & fine particles (0.25 

mm 

size) are 

important for

good

flow.



350 

to 

400 Kg/ 

M

3 

of fine 

particles 

are 

necessary

for

flow.



Slump 

of 

pumpable concrete is above 75

mm.

PROBLEMS IN

PUMPING

48



Blockage in

pipe



Pipe should 

be 

cleaned after each

day

operation



Blockage 

can be 

cleaned 

by

forward-

backward

pumping.



Tapping 

pipe with

hammer



Clean pipe 

with rod or 

sponge ball

pushed

by compressed

air.

PLACING

CONCRETE

49



Must 

be 

placed 

in systematic

manner.

Can be 

placed 

with 

following

methods:



Within earth mould 

:

Foundation



In 

timber plank 

formwork : 

Road,

airport

slab.



Steel shuttering 

:

Dam



Under

water

Concrete in

Foundation

50



In 

foundation, ground 

is made

wet.



Plastic sheet are laid between ground 

&

slab



Concrete is dumped 

not

poured.



No heap and

dragging



Placed in layers 

of 

35 

– 

40 

cm 

in 

mass

concrete



Avoid cold joints between 2

layers



Surface 

of 

previous layer is cleaned with wire

brush



Sometime, 

cement slurry 

is 

placed 

on old

surface



Top of 

previous layer 

kept 

rough 

for 

good

bond.

Concrete on Road, airport, floor

slabs



Placed in 

alternate bays (allow

shrinkage)

with contraction 

joints

:

contraction

joints

Bays

51

Concrete in Beams &

Column

52



Reinforcement 

correctly

placed.



Correct cover

required



Joints 

of 

shuttering 

to be

plugged.



Mould releasing agent inside

formwork

STRIPPING

TIME

53



Form work should 

not 

removed until good

strength 

has

 come.

UNDER WATER

CONCRETE

54

UNDER WATER

CONCRETE

55



Tremie (means hopper) 

is

used.



Funnel 

on

top



Pipe 

of 

200 

mm

size



Pipe bottom 

is

plugged



Fill pipe with

concrete



Lift 

pipe 

or jerk 

to 

release the

plug



Keep bottom 

of 

pipe inside

concrete

Underwater

Concrete

56



No 

compaction required 

as 

hydrostatic

pr

of 

water 

compacts

concrete.



Concrete of 0.3 W/C 

ratio 

can be

placed

with

Tremie.



Used for Pile or well

foundation

SLIP FORM

TECHNIQUE

57

2



In 

this method, concrete 

is 

continuously 

placed, 

compacted 

& form 

work

is

pulled up 

for 

next layer 

of

concrete.



Vertical slip 

form for 

Tall 

structure 

like silo,

chimney



Horizontal slip 

form 

paver machine 

(HSFP) for 

road

construction.



Concrete is dumped in front of 

HSFP 

machine by

dumpers.



Compaction by vibrator installed inside HSFP

machines.



Finishing 

of 

surface by 

HSF

paver.



Operation 

of 

road alignment, gradient, curve are controlled by

Computerized Laser Control

system.



Speed 

of 

construction is 1 

mt

/min.



1 km of 

concrete road of 3.75 

mt 

width 

is 

built 

in 

one 

day (16 

hrs

work).



Mumbai-Pune 

Expressway 

was 

constructed by 

this

machine.

VERTICAL SLIP

FORM

58

HORIZONTAL SLIP FORM ROAD

PAVER

59

COMPACTION OF

CONCRETE

60



Compaction is a process of expelling the entrapped air

inside

concrete

mass.



During mixing, transporting & placing the concrete, air gets

trapped

in concrete

mass.



If this air is not removed, concrete will not get

strength.



5 % of air voids reduces strength by 30

%



10 % of air voids reduces strength by 50

%



Durability of concrete is also reduces with air

voids.



Insufficient compaction increases permeability of

concrete.



Results in entry of aggressive chemicals in

solution.



Chemicals attack concrete & reinforcement and 

life 

of 

concrete

is

reduced.

METHODS OF

COMPACTION

61

1.

Hand

compaction

2.

Compaction by

vibration

3.

Compaction by pressure

&

jolting

4.

Compaction by

spinning

(2) 

COMPACTION BY

VIBRATION

62

a)

Internal

Vibrator

b)

Formwork

Vibrator

c)

Table

Vibrator

d)

Platform

Vibrator

e)

Surface

Vibrator

(1) 

HAND

COMPACTION

63



Hand

Rodding

Poking inside concrete with 

1-2 

mt long 

steel

rod



Ramming

Unreinforced 

foundation & ground floor

work



Tamping

Wooden beam is 

used 

to 

beat concrete 

(low

thickness 

slab, 

road

slab)

COMPACTION BY

VIBRATION

64



In 

hand compaction 

w/c ratio is 

more

so

we 

get 

less 

strength 

in

concrete.



In 

mechanical 

vibrator w/c can be kept

low

so we 

get good

strength.

INTERNAL

VIBRATOR

65

(a) INTERNAL

VIBRATOR

66



Most common in

use



Called, Needle Vibrator 

or Immersion vibrator or

Poker

vibrator.



Consists : electrical/diesel 

power 

supply, 

Needle

and

shaft.



Frequency of 

vibrations 

can be 

12000 

cycles

vibration per minute.



Needle diameter 20 to 75

mm



Length 25 to 90

cm.



Portable.

FORMWORK

VIBRATOR

67



Used 

for columns, walls, 

precast

slab



Vibrator 

is 

clamped 

to

formwork



Vibration 

is 

given 

to

formwork



Vibration 

is 

transferred 

from formwork

to

concrete



Useful in 

thin 

wall where

reinforcement

obstruct the 

needle 

type

vibrator.



Efficiency is 

lower then needle

vibrator

TABLE

VIBRATOR

68



Vibrator 

is 

clamped 

to

table



Used for concrete test

cubes



Cubes are 

kept on 

table 

to 

get

vibrations



Also 

used 

for small 

prefabricated

slab

TABLE

VIBRATOR

69

PLATFORM

VIBRATOR

70



Similar 

to 

table vibrator but of 

large

size



Used for 

long concrete electrical

pole,

railway 

sleeper,prefabricated roofing

element

PLATEFORM

VIBRATOR

71

SURFACE

VIBRATOR

72



Known 

as

Screed

Board

Vibrator



Used for 

thin roof 

slab where

needle

vibrator can 

not 

be

used



Not 

effective 

if 

slab 

thickness is 

more

then

15

cm.

SURFACE

VIBRATOR

73

COMPACTION BY PRESSURE &

JOLTING



Used 

for hollow 

blocks, solid

concrete

blocks



Stiff 

concrete is 

vibrated, 

pressed &

given

jolts



Stiff 

concrete is compacted to 

get

dense

form & 

good strength 

is

achived.

74

VIBRATION BY

SPINNING

75



New

method



Used for concrete

pipes



Concrete when spun at 

high 

speed

gets

compaction 

by 

centrifugal

force

VIBRATORY

ROLLER

76



Road rollers has vibrating

system



Roller while moving 

on 

raod 

slab

gives

vibrations



Used for 

Lean 

concrete 

(M10) 

for

road

base



ROLLER

VIBRATOR

77

PRECAUTIONS 

IN VIBRATING

CONCRETE



Vibrator gets damaged 

if 

comes 

in

contact

with 

hard object (Formwork, hard

concrete)



Switch on 

when needle 

is inside

fresh

concrete

mass



Should 

conform to IS

2505-1963



Degree of compaction can be

recognized

from rising 

air bubbles 

& 

formation 

of

thin

film on

top

78

HYDRATION OF

CEMENT

79



Cement 

is made by 

Cao, SiO

2

, Al2O

3

, Fe

2

O

3

, 

MgO,

K

2

O,

SO

3



After 

burning in Kiln following products are

made:

- Tri 

calcium

silicate

–

Di cacium

silicate

3Cao. SiO

2

(C

3

S)

2Cao.

SiO

2

(C

2

S)

3Cao. Al

2

O

3

(C

3

A)

– Tri 

cacium

aluminate

4Cao. Al

2

O

3

. Fe

2

O

3

(C

3

AF) -Tricalcium alumino

ferrite.

On 

addition 

of 

water 

in 

cement 

reaction 

of 

C

3

S, C

2

S, C

3

A

& 

C

3

AF liberate heat. Heat is suside by addition 

of

water.

CURING OF

CONCRETE

80



Curing 

is 

defined 

as 

“ 

making 

satisfactory 

moisture

content &

favourable

temperature”

in concrete 

after

placing 

the concrete. 

So 

that 

hydration 

may 

continue

until 

the 

strength 

is

developed.



Curing 

is 

required immediately 

after 

placing

concrete.



During hydration, heat 

of 

hydration is

released.

CURING OF

CONCRETE

81



Concrete delivers 

its strength by the 

hydration 

of

cement

particles.



Hydration is continuous 

& 

long 

time

process.



Rate 

of 

hydration is 

fast 

immediately 

after 

making 

the

concrete



Theoretically 0.23 

w/c ratio 

required 

for

hydration



0.15 

w/c 

ratio required 

for 

filling 

the 

voids in

gel.



Total 

0.38 

w/c 

ratio is optimum



In 

field condition, water evaporates 

& 

available water

quantity reduced 

for

hydration



Extra water is given by

curing

METHODS OF

CURING

82

a)

Water curing

b)

Membrane

curing

c)

Application of

heat

d)

Other

methods

WATER

CURING

83

a)

Immersion 

: 

Slab is 

kept 

in water

tank

b)

Ponding: 

Roof slab is 

filled 

with

water

c)

Spraying 

: 

water 

spary 

on 

concrete 

wall

is

d)

Wet covering : 

Wet gunny bags on

wall

MEMBRANE

CURING

84



Concrete surface is covered by

plastic

membrane



It 

is 

used where 

water availability 

is

less.



Plastic 

sheet 

reduces 

evaporation

in

concrete



Membrane 

is 

applied after 

2 

days 

of

water

curing

APPLICATION OF

HEAT

85



Spraying 

of steam on concrete 

provides heat 

&

moisture.



Higher temperature accelerates hydration 

rate & 

strength

of 

concrete is

attended



Early 

strength of structure 

is

obtained



Steam 

application possible 

at precast factory

only.



Precast 

prestressed concrete girders 

of 

bridge are cured

with

 steam



Fast 

construction of

bridge

HIGH PRESSURE STEAM

CURING

86



Superheated 

steam at 

high pressure 

(8.5 

kg/cm2) 

&

high

temperature(175 deg C) is applied on

concrete.



This process is called

“Autoclaving”



28 days strength of concrete is achieved in one

day



Concrete becomes sulphate

resistant



Low shrinkage in

concrete



Used in production 

of 

Cellular 

concrete 

products(

Siporex,

Celcrete)

FINISHING OF

CONCRETE

87



Finishing 

is 

last operation 

of 

concrete

making.



Finishing 

of top 

surface is required in roads, airport

strip, home

floor

Methods 

of

Finishing:

a)

Form 

work

Finish

b)

Surface 

Treatment

c)

Applied

Finishes

FORMWORK

FINISH



Concrete obeys 

the shape 

of

formwork



Grooves & 

lining 

on formwork 

plate

gives

makes grooves & 

lining 

on

concrete



Prefabricated tiles 

can be 

made 

of

any

design

SURFACE

TREATMENT

88



Domestic floor should 

be smooth, 

wear 

resistant,

crack

free.



Mix 

should have good proportion without excess

“Matrix”



Exposed aggregate finish 

: 

Colored pebbles on 

top 

layer

of

 wall



Bush Hammering 

: 

Electrically operated Brush with 

teeth

when applied on concrete 

removes top cement 

layer,

exposes aggregates and 

makes 

shining

aggregates.

APPLIED

FINISH



Rough cast 

finish 

: 

mixture 

of 

cement, sand,

round

gravel is applied on

wall



Non slip 

finish: 

Railway platform 

& 

walkway

around

pool are given non slippery finish by 

mixing 

large size

sand particles 

in 

floor

concrete.